It said many of the 100 pairs that nest in small colonies in the southern Pennines might be affected. The bird used to occur much more widely in England – there are greater numbers in western Scotland,

The seed-eating bird – a relative of the linnet – has clung on in the area because of the relative abundance of seed-rich hay meadows.

Fires have struck both its nesting and feeding sites, said the RSPB. Peter Robertson, its northern regional director and a member of the multi-agency England Twite Recovery Project, said: "Even before these fires, the twite was one of England's most threatened birds. But blazes have possibly affected more than a third of the English population.

"This could be a devastating setback for this bird. We have been working hard with farmers to help retain landscape features, like hay meadows, which are crucial to the bird. But inevitably England's most threatened finch has been hit hard by these fires. We hope that the bird will have a future in England."

Heathland that is important for other threatened birds, including the nightjar, woodlark and Dartford warbler, has been damaged across southern England. And the fires in other parts of the UK will undoubtedly have affected ground-nesting birds, according to the RSPB.

Nick Phillips, a policy officer, said: "Some of the most threatened birds in the UK nest on the ground. We are currently in the middle of the nesting season, with many birds incubating eggs or tending to chicks. Fire is a considerable risk to these birds, and other threatened wildlife, such as reptiles.

"A break in the dry weather may bring a brief respite, but we are still urging people to guard against any risk of wildfire."